[TG] Rv100 shows deep depth falsely

[Quinn h pearson]

Got a pair of axiom 9’s with an rv100 transducer and a b60 connected via the Y cable.

When I leave the dock at 3 knots, the sounder will show 899 plus feet of water in only 25 feet until I get up to 15 knots or better and then it’s fine for the day.

The transducer is clean, just a bit of growth on the sides but none on bottom, and if I go out on the water tomorrow , the same thing will happen so there’s no way I’m growing enough slime in one day to do this.

The b60 is in the hull at mid ships and always performed fine when it was connected to my old c120

All equipment is software updated as of July 2018

Why the deep reading when I first leave?

[Tom - Raymarine - Moderator]

Can you post some clear, full-screen, high-res photos or screenshots of the sounder image at the time, so we can see what you're seeing?

What sounder channel are you looking at at the time, do you know - Chirp Sonar, RV3D, DV, SV, 200kHz or 50kHz? (If you're not looking at the sounder image when the problem happens, please turn on the sounder page so that we can see where the false depth data might be coming from.)

Thanks,
Tom

[Quinn h pearson]

(07-18-18 01:58 AM)Tom - Raymarine - Moderator Wrote:  Can you post some clear, full-screen, high-res photos or screenshots of the sounder image at the time, so we can see what you're seeing?

What sounder channel are you looking at at the time, do you know - Chirp Sonar, RV3D, DV, SV, 200kHz or 50kHz? (If you're not looking at the sounder image when the problem happens, please turn on the sounder page so that we can see where the false depth data might be coming from.)

Thanks,
Tom

I’m in traditional mode or in 3D mode when the false depth happens. In traditional mode it’s set to auto so I’m guessing it’s at 200 kHz when I’m shallow at the dock (25 feet)

Will grab some screen shots if I can but as luck would have it, I sold the boat today and only have till Saturday to correct this before new owner gets it

[Tom - Raymarine - Moderator]

In the meantime then, can you describe the sounder image (in traditional/200kHz, let's not worry about 3D for now as it is much more complex)?

Have you tried Manual Range, setting the range to something a bit deeper than the expected depth?

How sure are you that this is a speed-related problem, working at higher speeds, and not for example related to a change in bottom conditions that perhaps coincides with you leaving a no-wash zone or similar? If you're sure it's speed, not location that's the factor that makes it work, there are three things that spring to my mind:
- poor flow of water or aeration across the transducer face when the boat is displacement/ploughing but not when planing
- a noise signal related to speed, e.g. hull section resonating with a harmonic of engine revs (this really happens, and just like a rattle in your car - or at least my car - is engine-rev-range specific)
- low supply voltage to the display, starving the sounder ping reservoir and preventing proper sounder power output, which is resolved when you get some surface charge in the batteries.

Tom